Hoisting apparatus



P 14, 1954 J. A. OLSON HOISTING APPARATUS I5 Sheets-Sheet 1 Filed Oct.18, 1948 INVENTOR. z-fomv A. OLSON /Q7'r0 Q/v5 Sept. 14, 1954 J. A.OLSON HOISTING APPARATUS 3 Sheets-Sheet 2 Filed Oct. 18, 1948 I NVENT0R.

'dC H/V A. OLSO/V,

BY f4 firTaQA/EY.

Sept. 14, 1954 J. A. OLSON 2,689,053

HOISTING APPARATUS Filed Oct. 18, 1948 3 Sheets-Sheet 3 INVENTOR.

db/75v A. 04.50,

BY W QTTQQNEY.

Patented Sept. 14, 1954 HOISTING APPARATUS John A. Olson, Long Beach,Calif., assignon'by mesne assignments, to Lourie L. Eakin, Ventura,Calif.

Application October 18, 1948, Serial No. 55,069

4 Claims.

The present invention relates to hoisting apparatus, and to mechanicalmovements that may form part of such apparatus.

Certain types of hoisting apparatus may employ a pivoted boom in liftingand transporting a load from one point to another. The boom may be swungthrough a substantial arcuate extent to occupy various positions, whichmay range from substantially horizontal in one direction, through thevertical, to substantially horizontal in the opposite direction. When aload is carried by the free end of the boom, a greater torque isrequired to swing the boom from the substantially horizontal positionsbecause the moment arm is greater. As the boom approaches the vertical,the effective moment or lever arm of the load decreases, and the torquerequired to swing the boom decreases, correspondingly.

Heretofore, a fluid or hydraulically operated cylinder, piston and crankmechanism has been coupled directly to the boom in effecting itsswinging to the various positions above noted. The line of applicationof the hydraulic force provided by the cylinder and piston is locatedclose to a dead center crank position, or coplanar with the crankmechanism, when the boom is substantially horizontally disposed. When inthis position, the effective lever arm of the piston device on the crankis at a minimum value, and this minimum value occurs at a time when thetorque load on the crank is at a maximum, in view of the horizontaldisposition of the boom. Conversely, when the boom is in a verticalposition, the torque load on the crank is at a minimum, but at thistime, the effective lever arm of the piston device on the crank is at anunrequired maximum, at which the hydraulic mecha nism is capable ofimposing a maximum torque on the crank.

The foregoing arrangement and disadvantageous conditions are foundparticularly in boom hoisting apparatus mounted on motor trucks,trailers, boats, barges, and similar vehicles. In such vehicles, it isdesirable to mount the operating mechanism as much as possible under thevehicle bed or load carrying platform. This is desirable, and has notheretofore been attainable without some interruption in the continuityin the bed or platform, which interferes with the load carryingutilization and capacity of the vehicle.

Accordingly, an object of the invention is to provide an improvedhoisting apparatus capable of imposing an increased torque on thehoisting boom when the latter occupies substantially horizontalpositions, or positions approaching the horizontal.

Another object of the invention is to provide a hoisting apparatus, inwhich the effective lever arm of the prim mover mechanism on the crankmechanism is increased when the boom occupies its substantiallyhorizontal position or positions.

Another object of the invention is to provide an improved hoistingapparatus capable of operating under more uniform load conditions on theprime mover as the boom is shifted between horizontal and verticalpositions.

A further object of the invention is to decrease the effective lever armof the prime mover mechanism on the crank mechanism as the effectivelever arm of the load on the boom decreases, thereby preventing wideload variations on the prime mover mechanism.

Yet a further object of the invention is to provide a hoisting apparatusparticularly adapted for use on a vehicle, in which the apparatus doesnot interfere with the vehicle load carrying platform or bed, thehorizontal surface of the latter remaining uninterrupted.

Still another object of the invention is to provide a hoisting apparatusembodying operating mechanism which requires less vertical distance forits operation, thereby enabling the mechanism to occupy a lesservertical space.

A further object of the invention is to provide a hoisting apparatus inconjunction with a vehicle platfornnin which the hoisting boom iscapable of forming a continuation of the platform when not in use forhoisting purposes.

Still another object of the invention is to provide a hoisting apparatusembodying a crankshaft connected to the hoisting boom, which does notinterfere with the movement or range of movement of the prime movermechanism coupled to it.

Yet another object of the invention is to provide an improved mechanicalmovement for varying-the throw of the crank mechanism. Such throw isincreased or decreased in accordance with the load requirements on themechanism, or in accordance with the particular instantaneous positionthat the mechanism occupies.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of severalforms in which it may be embodied. Such forms are shown in the drawingsaccompanying and forming part of the present specification. These formswill now be described in detail, illustrating the general principles ofthe invention;

3 but it is to be understood that such detailed description is not to betaken in a limiting sense, since the scope of the invention is bestdefined by the appended claims.

Referring to the drawings:

Figure 1 is a perspective view, with parts being broken away, of ahoisting apparatus as installed on a motor vehicle;

Fig. 2 is a diagrammatic side elevation of the operation of the boomportion of the hoistin mechanism;

Fig. 3 is a longitudinal section through the prime mover and crankportion of the hoisting device;

Fig. 4 is an enlarged section taken along the line 4-4 on Fig. 3; h

Fig. 5 is a fragmentary section taken along the line 5-5 on Fig. 3;

Fig. 6 is a somewhat diagrammatic view, similar to Fig. 3, illustratingthe crank mechanism in another operative position, and also disclosingthe hydraulic control system for the hoisting apparatus;

i Fig. 7 is a somewhat diagrammatic view, similar to Fig. 3, of aslightly modified form of the invention; and

1 Fig. 8 is a diagrammatic representation of the variable effectivemovement of lever arms obtainable by the apparatus disclosed.

The hoisting apparatus is disclosed in the drawings as applied to amotor truck I having the usual side channels or rails II of the chassis,which support the bed or platform I2 disposed to the rear of theoperators or drivers cab I3.

. The hoisting mechanism is carried by the chassis channels I I. Asshown most clearly in Fig. 4, the mechanism, with the exception of theboom, is disposed within a suitable enclosure including a central,longitudinally extending housing I4 for the hydraulic prime movermechanism and crank mechanism, and transverse tubular housings IS onopposite sides of the central housing, extend ing through the chassischannels I I to a point outside the truck platform I2. The tubularhousings I are suitably secured to the central housing I4 and serve as ameans for supportin the latter. A tubular crankshaft mechanism idisposed within the housings I4, I5. This mechanism has oppositelydirected tubular shaft portions I6 rotatably supported in bearings H, inthe tubular housing members I5. The shafts extend beyond the outer endsof the, tubular housings I5, where they are connected to the sidemembers I 8 of the boom I9 and provide a pivotal support for the boom.Each side member includes a leg portion 20, which is adapted to lieadjacent the side edges of the bed I2, and a foot portion 2 I, integralwith the leg portion, which extends transversely to the latter in orderthat both opposed foot portions may be welded, or otherwise suitablysecured, to a triangular boom portion 22, which is offset with respectto the leg portions 20. This triangular portion includes a pair ofinclined members 23 suitably welded, or'otherwise secured, to the footportions 2! and joined together at their apex to provide a suitablerotatable support for a sheave or pulley 24. A cross brac 25 extendsacross the ends of the foot portions 2| and is suit ably welded, orotherwise secured thereto to complete the triangular section 22. Thiscross brace 25 carries a chafing roller 26, over which the cable 2] ofthe hoisting mechanism may ride.

The offset portion 22 of the boom I8 is provided to allow it to bedisposed snugly along and over tion when the boomv I8 is not in use, inwhich position the upper edges 20a of the leg portions 20 preferablyoccupy a position substantially ooplanarwith the upper surface of thetruck platform I2, thereby increasing the effective area of theplatform. The boom I8 may be swung from the collapsed position over thevehicle It disclosed in Fig. 1, through a generally vertical positionand i to a rearward, substantially horizontal position,

in which the sheave 24 at the end of the boom extends a substantialdistance beyond the axis of the crankshaft (see Fig. 2)

Regardless of the position which the boom occupies, it may beoperatively connected to a suitable load or weight W by means of thecable 21. As disclosed in the drawing, the cable extends around thewinding drum 28 of a power winch 29 located adjacent the operators cabI3. This winch may be operated in-a known manner by the truck enginethrough a suitable power takeoff device (not shown).

The cable 21 extends from the windin drum 28, over the sheave 24 andacross-the chafing roller 26. The free end of the cable may be suitablysecured to the load W, as through the use of a crane hook 30 or thelike.

When the boom I8 is in position for raising and lowering loads, thepower winch 29 may be suitably operated to wind or unwind the cable 21from thedrum 28, and correspondingly raise or lower the load. When thesheave axis is disposed forwardly of the chafing roller axis, the cable2'! is still free to operate, since the engagement of the cable with theroller 26 will merely rotate the latter, since it functions as a guidingor idler roller.

The pivoting of the boom I8 about the crankshaft axis is accomplishedthrough suitable manipulation of the crank mechanism. This crankmechanism includes adjustable crank arms 3I secured to the inner ends ofthe tubular shaft members I6, carrying a crankpin 32 at their outerends, on which the end of a piston rod 33 is pivotally mounted betweenthe crank arms 3!. The piston rod is connected to a piston 34 slidablewithin a cylinder 35, having its head end 36 oscillatably mounted upon ahinge pin 31 secured to the housing I 4. Fluid may enter the head end ofthe cylinder 35 through a suitable conduit 38 to move the piston 34' andpiston rod 33 rearwardly.

It may also enter the rod end 39 of the cylinder 35 through a suitableline or conduit 40 to move the piston 34 and piston rod 33 in theopposite direction. Durin this movement, the cylinder may accommodateitself to the vertical shifting of the piston rod 33 by rocking upon itshinge pin 31.

A system for controlling the entry and discharge of fluid into thecylinder 35 is illustrated in Fig. 6. The conduit or intake and exhaustline 38, to the head end 36 of the cylinder is connected to a suitablecontrol valve M, which may have a manually operable lever Ma. Similarly,the intake and exhaust line 40 runs from the rod end 39 of the cylinderto the control valve 4|. Fluid under pressure may be supplied to eitherend 36 or 39 of the cylinder by an oil pump 42, that may be driven bythe truck motor through a suitable power take-on device (not shown) Thefluid pressure pump 42 draws oil from a suitable sump or reservoir 43,which may be located at the lower portion of the central housing l4,through a suction line 44, in which a filter 45 may be interposed. Thepump 42 discharges the oil into another pipe 46 running to the controlvalve 4!, from where the oil under pressure may pass to either the heador rod end 36 or 39 of the cylinder 35 through their respective intakeand exhaust lines 138, 40, depending upon the position of the controlvalve.

The control valve 4|, by itself, forms no part of the present inventionand is Well known. When in one position, the pump 42 may supply oilunder pressure to the head end 33 of the cylinder, the rod end 39 of thecylinder and its conduit '40 being arranged for an exhausting condition,the fluid from the rod end passing from the valve 4! through a returnline 4! to the oil reservior 43. Conversely, the control valve 4! may bemanipulated, so that the line 38 running to the head end 36 of thecylinder exhausts through the return line 41 to the reservoir 43, whilethe line 40 running to the rod end 33 of the cylinder receives fluidunder pressure from the pump 42.

As an alternative arrangement, a separate oil reservoir 48 may be used,from which the pump 42 draws oil, or other fluid, through a filter 49into its intake or suction line 44.

Any excess fluid displaced by the pump 42 may flow back to the suctionline 44 through a bypass 50, which includes a pressure relief valve 5|that will open at a predetermined pressure, so as to avoid theimposition of too great a pressure in the cylinder 35. As aprecautionary measure, safety check valves 52 may be incorporated in theintake and exhaust lines 38, 48 leading to the cylinder.

Since the boom I8 is secured to the crankshaft portions l6, operation ofthe cylinder and piston mechanism will rotate the crank mechanism toeffect a corresponding pivotal movement of the boom. The cylinder andcrank mechanism is arranged to avoid the piston rod ever being in a deadcenter position, whether such position is head end dead center or crankend dead center. The range of movement of the piston 34 in the cylinder35 is such as to swing the crank arms 3| through a comparatively wideangle. As an example, the crankshaft might swing through an angle ofabout 160 degrees in shit"- ing the boom 118 from a forward, generallyhorizontal position adjacent the truck platform i2 and over theoperators cab l3, to a rearward, generally horizontal position, at whichthe boom is effective to elevate or place a load W from or on aparticular location.

When the boom is in its substantially horizontal positions 5 3, 54, suchas disclosed in Fig. 2, the eifective lever arm of the load W on theboom, or the lever arm of the boom, itself is at a maximum. Thus, asshown in Fig. 2, the lever arm of the load W in the extreme rightposition is the distance a. This lever armprogressively decreases as theboom is elevated towards a position 56, in which the load W extendsdirectly over the boom axis, and in which the boom I8 is considered asbeing vertical. As the boom is swung from this vertical position in aforward direction, the effective lever arm of the load W increasesagain. This lever arm is designated by b in Fig. 2.

The crank mechanism, however, when the effective lever arm of the load Wis at its maxi,-

mum, is located in such position that its effective lever arm is at itsminimum. This condition is represented diagrammatically in Fig. 8, inwhich it is evident that the effective lever arm 6 of the piston rod 33is muchsmaller than the eifective lever arm 1 of the piston rod when theboom is disposed vertically. Similarly, as the boom t8 moves forwardlyof the motor vehicle, the effective lever arm g of the piston rod 33 onthe crank decreases until it reaches a minimum when the boom is disposedin a generally horizontal position, with its forward end 22 over theoperator's cab I3.

From the foregoing, it is apparent that the eifective lever arm of thepiston rod 33 on the.

crank tends to be the least when the torque requirements on the fluidmotor 33, 34, 35 are the greatest, and that the lever arm tends to bethe greatest when the torque requirements are the least. This anomaloussituation is minimized by the present invention.

In the present invention, the effective lever arm of the piston rod 313on the crank mechanism is increased when the load W on the boom 18 isacting through a greater effective lever or moment arm. Also, theeffective lever arm of the rod 33 on the crank mechanism is decreasedwhen the moment arm of the load on the boom decreases. In this manner,the effective moment arms of the piston rod on the crank mechanism arebrought closer together in value, in order that the hydraulic primemover mechanism 3-5 may be subjected to a more nearly constant loadcondition during movement of the boom I8.

The foregoing objective achieved by varying the throw of the crank pin32 in accordance with the angular position of the crank arms 31. Thus,the crank pin 32 has a greater throw, or is located a greater distancefrom the axis of the crankshaft l 6, when the boom it occupies itssubstantialiy horizontal positions, than when the boom occupies itsvertical position. By referring to Fig. 8, it will be noted that byincreasing the distance of the crank pin 32 from the crankshaftaxis,'the effective lever arm of the rod 33 is increased. Thus, if thecrank pin is located distance r from the crankshaft axis, the effectivelever arm is e. If located the greater distance s from the crankshaftaxis (for the same position of the boom 18), the effective lever arm isthe greater distance 9. This condition pertains to an increased throw ofthe crank pin when the boomis disposed in either a forward or rearwardposition with respect to the vehicle. The decreasing" of the crank throwwhen the boom is in substantially its vertical position also reduces theeffective lever arm of the piston rod 'on the crank mechanism.

The particular apparatus disclosed in the drawing effects an automaticchange in the throw of the crank pin 32 in accordance with the angularposition of the crank arms 31 and of the boomlfl. Thus, each crank arm3! includes a guide member 683 suitably secured, as by welding, to theinner end It of the crankshaft. This guide member has a radial slot orgroove 61, in which a slidable crank arm portion 62 is mounted. The freeends of the slidable arm elements 62 are formed as bosses 33 in whichthe crank pin 32 is received, and beyond which the crank pin projects.

Follower rollers 64 are mounted on the outwardly projecting ends of thecrank pin, each roller being located within a cam groove 65 formed by aninner cam track member 66 suitably attached to the housing I4, and by anouter cam track member 61, which may be formed by the curved portion ofthe intermediate housing M. The cam groove 65 is shaped in such manneras to cause its portion 65a vertically below the crankshaft I6 to belocated a lesser distance from this shaft than the grooved portions 65!)disposed laterally or substantially horizontally of the crankshaft.Thus, as the piston rod 33 moves the crank arms 3| angularly, thefollower rollers 64 on the crank pin 32 ride within the opposedstationary grooves 65 to vary the distance of the crank pin 32 from thecrankshaft axis, thereby varying the throw of the crank pin 32 andeffective lever arm of the piston rod 33 on the crank arms 3|.

By referring to Fig. 3, it will be noted that the crank arm 3| isdisposed in a vertical position, corresponding to the vertical positionoccupied by the boom l8. The cam groove 65a is there located closer tothe axis of the crankshaft. As the piston 34 and piston rod 33 moverearwardly, to swing the crank arms 3| and crankshaft 6 in acounter-clockwise position to the location shown in Fig. 6, the followerrollers 64 ride in the cam grooves 65 and increase the length of thecrank arms 3! to increase the throw of the crank pin 32, which effectsan increase in the effective lever arm of the rod 33 on the crank arms3| and crankshaft I6.

Similarly,. shifting of the piston rod 33 in the opposite direction, toa position in which the crank arms 3| approach the right, causes thefollower rollers 64 riding in the cam groove 65 to increase the lengthof the crank arms 3| and the throw of the crank pin 32, in order tocorrespondingly increase the effective lever arm of the rod 33 on thecrank mechanism.

The foregoing is diagrammatically illustrated in Fig. 8. If the throw ofthe crank pin 32 is assumed to be 1', the effective lever or moment armof lever 33 when the boom I8 is in its forward, generally horizontalposition will be at the distance e. If the crank throw is increased tothe distance s, it is evident that the effective lever arm is increasedconsiderably to the distance 9, for the same angular position of thecrank mechanism and boom.

It is, accordingly, apparent from the foregoing description that thetorque that can be imposed by the prime mover mechanism on the crankmechanism is increased when the torque requirements are greatest, and isdecreased when the torque requirements are of lesser extent. In thismanner, the load on the hydraulic prime mover mechanism isprevented fromfluctuating widely and is more nearly constant.

A modified form of variable throw crank pin device is disclosed in Fig.'7. In this form, crank arms 3|a are secured to the inner ends of thecrankshaft portions l6. These arms are provided with generally radialslots or guides 10, in which bearing blocks 1| are slidable. The crankpin 32' is mounted in these bearing blocks and extends beyond thebearing blocks, where the follower rollers 64 are mounted on them. Theserollers are movable within the cam grooves 65, in the same manner as inthe other form of the apparatus. As in the other form of the invention,the end of the piston rod 33 is p-ivotally mounted on the crank pin 32between the crank arms 3 Ia.

It is apparent that as the piston 34 moves within its cylinder 35, toshift the rod 33 and rock the crank arm 3|a and crankshaft members I6,the follower rollers 64 ride in the grooves 65 and 8 cause the guideblocks H to move within the radial slots 10 of the crank arms 3 I 11,thereby varying the distance of the crank pin 32 from the crankshaftaxis.

It is to be noted that there are no elements of the mechanism projectingthrough the vehicle platform |2, which retains an uninterrupted surfacefor the loading, conveying and unloading of articles. In this manner,the capacity of the vehicle is increased. By decreasing the length ofthecrank arm 3| or 3| a as it moves through the vertical position, themechanism extends below the truck platform |2 to a lesser extent,requiring less vertical space below the truck bed for the device. Byproviding the divided crankshaft arrangement, in which the piston rod 33is movable between the crank arms 3| or 3|a, the crank shaft I6 may bemoved by the rod 33 to a greater angular extent, which enables the boomIt to be moved through acorrespondingly greater angular extent, allwithout interference from the crankshaft IS.

The inventor claims:

l. A hoisting apparatus comprising a chassis, a horizontal pivotalsupport onsaid chassis,*a boom fixed on said pivotal support for raisingand lowering movements from a first substantially horizontal positionthrough the vertical and to a second substantially horizontal positionin the opposite direction, a crank arm on said pivotal support, a crankpin slidably mounted on said crank arm for movement toward and from theaxis of the pivotal support, a cam connected to said chassis and meansoperatively connected to said crank pin and engaging said cam forpositively moving the crank pin so that the crank pin is closest to thepivotal axis when the boom is in its vertical position and so that saidcrank pin is farthest from said pivotal axis when the boom is in eithersubstantially horizontal position, and means for applying a force onsaid crank pin in a direction transverse to the axis of the pivotalsupport whereby the crank pin and the boom are moved through an anglesubstantially greater than a right angle and approaching a straightangle so that the mechanical advantage eifective for raising andlowering the boom more closely approaches the load re-- quirements thana fixed crank pin.

2. The invention according to claim 1 in which the crank arm has aradially extending guide groove, arm elements slidably mounted in saidguide groove of said crank arm, and the crank pin is fixed on said armelements so that the crank pin may move radially toward and from theaxis of said pivotal support.

3. The invention according to claim 1 in which the crank arm is providedwith a radially extending slot and the crank pin is slidably mounted insaid radially extending slot and the crank pin includes a portionprojecting from said crank arm and into positive operative relation tosaid cam.

4. A vehicle having a flat bed for supporting a load, a pivotal supportmounted below said flat bed for rotation about an axis which issubstantially horizontal, boom members fixed to the pivotal supportoutside of the outlineof the fiat bed, said boom members being connectedtogether at a location spaced from the pivotal support, and having aclear space therebetween for a substantial distance from the axis to theconnected together location, said boom members being so shaped that asubstantial portion of the length thereof lies below the upper surfaceof the flat bed for maintaining a substantally unobstructed fiat bedwhen the boom is in its stored inoperative position, said boom membersbeing movable to a substantially horizontal position in an oppositedirection from said stored position, a crank arm fixed on said pivotalsupport and extending in a radial direction generally opposite thedirection of said boom members so that the crank arm is maintained belowsaid flat bed at all timesfi means for monuting a crank pin on saidcrank arm for movement toward and from said axis, a cylinder and pistonmounted on said chassis and connected to the crank pin for moving saidpivotal support and the boom memers carried thereby through an angleapproaching a straight angle, a cam mounted in fixed relation withrespect to said chassis and engaging said crank pin and shaped to movesaid crank pin toward said axis when the boom members are generallyvertical and .to move said crank pin away from said axis when the boommembers are in either substantially horizontal position.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Name Date Emerson June 28, 1904 Bracken June 20, 1911 Broady Aug.23, 1921 Palotce Aug. 31, 1926 Boling Dec. 1, 1931 Tetrault Mar. 15,1938 Willis Nov. 28, 1939 Amery Mar. 20, 1945 'E'akin May 22, 1951 EakinNov. 13, 1951 FOREIGN PATENTS Country Date Great Britain Aug. 12, 1940France Apr. 26, 1948

